Alcohol fermentation from sugar-containing raw materials occupies a large proportion of brewing wine and alcohol industry, however, due to the inherent characteristics of sugar-containing raw materials such as single nutrition, lower pH buffer capacity and the like, the sugar-containing raw materials fermentation by using common leaven can not implement completely, especially under the condition of high alcohol concentration. As an example by using sucrose, the common leaven only can maintain the alcoholicity of fermentation in the level of 11-13% v/v, if the alcoholicity continues increasing, the residual sugar-containing raw materials content will become higher and the utilization ratio of the raw materials is deteriorated. Therefore, the issues that how to improve the nutrition condition of the mash of alcohol fermentation from sugar-containing raw materials and how to utilize the raw material components completely are needed to resolve urgently.
As to alcohol fermentation from sugar-containing raw materials, the prior art only directly carried out the fermentation by using yeast or supplied the part of nitrogen source. Furthermore, the prior art did not scientifically analyze the nutrition composition of the fermentation liquor of alcohol fermentation from sugar-containing raw materials, and also did not provide the necessary nutrition for yeast growth, accordingly, the fermentation liquor was not able to be fermented completely, such that the residual sugar content of the mash becomes higher and the utilization ratio of the raw materials was deteriorated.
In addition, Chinese Patent Application Publication No. CN1710084A disclosed a clear process for ethanol fermentation production by using the purified juice of the sugar crops, comprising the step of: A. clarified the mixture solution squeezed from the sugar crops by using bentonite-chitosan complex flocculant clarification technology, and then the separated filtered mud can be used as organic fertilizer, the amount of the pollution is decreased from the source; B. concentrated the purified juice into about 23% sugar content, and proceeded the fermentation by using the concentrated the purified juice and adding yeast thereto, such that the ethanol component of the maturing mash is improved more than 12%, and the discharge of the waste liquid is decreased; C. after the fermentation mash is distilled, the waste mash obtained is subjected to a multiple effect distillation concentration and used as animal protein feed, and achieving none of the waste mash are discharged, solving the problem of the waste mash pollution of the ethanol production.
However, this patent application needed to carry out the bentonite-chitosan complex flocculant clarification technology to the squeeze of the sugar crops, furthermore, needed to concentrate the flocculated sugar cane purified juice and allowed the sugar content reach to about 23%, so it needed some auxiliary equipments such as an additional rapid settling vessel, frame filter and the like, thereby the equipment cost of the process for ethanol fermentation production by using the purified juice of the sugar crops was sharply increased, in the examples, the ethanol composition only reached to 12.6%, the residual sugar content was 0.1%, so the cost of the process for ethanol fermentation production from the purified juice of the sugar crops increased.
For the purpose of overcoming the defect of the prior art, on the basis of fully considering the nutrition condition of sugar-containing raw materials fermentation liquor and the cost of the equipment, the present invention provides a composite yeast suitable for high concentration alcohol fermentation from sugar-containing raw materials. The composite yeast is comprised of a dried yeast and a nutrition source, wherein the dried yeast is a leaven, having strong fermentation activity for the sugar material; the nutrition source includes a inorganic salt or a organic salt, a microelement and a bacteriostatic, providing the necessary nutrition for yeast growth and fermentation, and also inhibiting the other bacteria proliferation, and finally implementing the complete and quick fermentation of sugar-containing raw materials, thus the utilization ratio will be improved without an additional pretreatment to the sugar materials, and the equipment cost of the process is decreased, the alcohol fermentation from sugar-containing raw materials can be proceeded by using the original equipments, and then will implement the complete and quick fermentation of sugar materials, and the utilization ratio of the raw materials will be improved.